1. Field of the Invention
The present invention relates to gas turbine engines and, more particularly, to a diffuser for directing a flow of compressed air with a radial component to a diffused annular flow having an axial component.
2. Description of the Prior Art
Conventional gas turbine engine diffusers comprise a machined ring which surrounds the periphery of a compressor impeller for capturing a radial flow of compressed air and redirecting it through generally tangential orifices into an array of diffuser pipes. Fabrication of the diffuser pipes is extremely complex since they have a flared internal pathway that curves from a generally radial tangential direction to an axial rearward direction. Each pipe must be manufactured to close tolerances individually and then assembled to the machined diffuser ring. Complex tooling and labor intensive manufacturing procedures result in a relatively high cost for the preparation of the diffusers.
In an attempt to reduce the tooling and the manufacturing costs, it has been proposed to manufacture a diffuser from two concentric nested shells see U.S. Pat. No. 6,471,475, secured together by brazing, one of the shells being provided with grooves separated by seam edges while the other shell is provided with a smooth surface of revolution. The groove on the one shell are closed by the other shell when the shells are nested together and the seam edges are secured to the smooth surface thus defining individual ducts extending continuously from the compressor impeller to the outer shell edges.
Although the above-described diffuser design greatly reduces the tooling and manufacturing costs associated with prior art diffuser assemblies, the pursuit of increased efficiency at decreased cost makes improvement ever-desirable.